The present invention, in some embodiments thereof, relates to energy conversion and, more particularly, but not exclusively, to a device and method for generating electricity. Some embodiments relate to a method suitable for fabricating a structure which can be incorporated in a device for generating electricity.
Energy conversion systems receive energy in one form and convert it to energy in another form. In many cases, mechanical energy, resulting for instance from heat engines, hydro, or wind power, drives the rotation of turbines resulting in the generation of electricity. In other cases, no moving parts are involved in the conversion process, such as in solid-state electricity generators. Closed electrochemical cells, commonly known as batteries, are but one example of such electricity generators, but are generally used for storage rather than meaningful electricity production, since their production is limited by the amount of chemical reactant contained in the battery. Open electrochemical cells, such as fuel cells which can be replenished (for example with hydrogen as the core reagent in the oxidation reaction producing the chemical energy to be converted) are more likely to be used for the general production of electricity. Both the closed and open devices share the principle that an irreversible chemical reaction is taking place between the electrodes and the electrolyte, or within the electrolyte, generally resulting in chemical degradation of parts of the devices, such as corrosion of the electrodes, or consumption of the fuel.
Additional energy conversion systems include thermoelectric, thermionic and thermotunelling devices, where thermal energy is converted to electricity. These devices generally rely on a high temperature gradient between a cold and a hot surface and/or on high operating temperatures. In most cases, the surfaces are in vacuum to ensure that the thermal gradient driving the electricity production is maintained. However, in some such devices, gases such as cesium vapor can be used to modify the properties of the surfaces and to prevent the formation of space charge near the electrodes.